A063702 - OEIS

A063702

Composite numbers k such that phi(k + d(k)) = phi(k) + d(k), where phi() = A000010(), d() = A000005().

24, 42, 56, 98, 102, 230, 248, 264, 294, 468, 638, 1014, 1016, 1078, 2006, 8366, 10344, 11914, 11918, 13158, 15694, 19942, 23318, 24734, 33496, 39348, 57352, 65528, 79826, 119799, 176606, 176874, 199048, 200152, 236006, 236174, 236530

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OFFSET

1,1

LINKS

Harry J. Smith, Table of n, a(n) for n =1..100

MATHEMATICA

cnkQ[n_]:=CompositeQ[n]&&EulerPhi[n+DivisorSigma[0, n]] == EulerPhi[ n]+ DivisorSigma[ 0, n]; Select[Range[240000], cnkQ]

PROG

(PARI) { n=0; for (x=1, 10^9, if (eulerphi(x + numdiv(x)) == (eulerphi(x) + numdiv(x)) && !isprime(x), write("b063702.txt", n++, " ", x); if (n==100, break)) ) } \\ Harry J. Smith, Aug 28 2009

CROSSREFS

Cf. A000005, A000010.

Sequence in context: A098769 A162886 A274350 * A074975 A077095 A228844

Adjacent sequences: A063699 A063700 A063701 * A063703 A063704 A063705

KEYWORD

nonn

AUTHOR

Labos Elemer, Aug 23 2001

EXTENSIONS

More terms from Dean Hickerson, Aug 24 2001

STATUS

approved